The invention relates to an apparatus for the controlled moving of a warp thread. It also refers to a weaving machine with an apparatus of this kind and to uses of the apparatus.
Leno apparatuses are used for the formation of selvedges: An eyed needle, which guides a warp thread in an eye, and a follower needle form a leno weave in interaction with a weft thread (see e.g. EP-A 0 737 764). The needles are moved by drive units which, in known weaving machines, comprise cable runs, control cams, rollers and levers. These mechanical components are expensive and prone to wear. When operating parameters (among others, heald stroke, shed geometry) are changed, time-consuming adjustments must be made by hand.
It is also known to use linear motors as drive units. An electronic processor, which is already used for the control of the weaving machine, can also be used for the control of the linear motors. In this it is however disadvantageous that control loops with special position sensors are required for the setting of warp thread layers using means which act point-wise--for example eyed needles (cf. WO 96/38608)